This invention relates in general to hub assemblies for automotive vehicles and more particularly to a hub assembly that better excludes contaminants from its interior.
Various arrangements exist for mounting the road wheels of automotive vehicles on the suspension systems of such vehicle. One arrangement relies on a dead spindle which projects from the suspension systemxe2x80x94usually from a steering knucklexe2x80x94into a hub to which a road wheel is bolted. The hub rotates around the spindle on antifriction bearings that are located between the hub and the spindle. In another arrangement, the hub to which the road wheel is bolted has a live spindle which projects into a housing which in turn is bolted to a steering knuckle or other suspension system component. An antifriction bearing located between the spindle and housing enables the spindlexe2x80x94and indeed the entire hubxe2x80x94to rotate relative to the housing.
The latter finds widespread use on four wheel drive vehicles and on front wheel drive vehicles, inasmuch as the spindle is easily coupled with a constant velocity joint at the end of a drive shaft. Yet it operates just as well with nondriven wheels, particularly the front wheels of rear wheel drive sport utility vehicles and light trucks. Thus, automobile manufacturers can offer four wheel drive vehicles and rear wheel drive only vehicles without changing the type of hub assembly for the front wheels.
Irrespective of the arrangement, the bearings that are located around the spindle must have barriers of one type or another to exclude contaminants from them. With a dead spindle, typically a seal is fitted to the inboard end of the hub, and it wipes a wear surface on the spindle. An end cap is pressed into the outboard end of the hub. With a live spindle used for a nondriven wheel, the outboard end of the bearing contains a live seal. Likewise, the inboard end of the bearing may be fitted with a live seal or the inboard end of the housing or the steering knuckle itself may be fitted with a cover that isolates the inboard end of the bearing, but this increases the expense of the hub assembly. On the other hand, when the live spindle is coupled to a drive shaft through a constant velocity (CV) joint, both the inboard and outboard ends of the bearing require live seals. Thus, to avoid variances between the front wheel hub assemblies for two and four wheel drive vehicles, some manufacturers choose to furnish all such hub assemblies with the seals at the inboard ends of their bearings.
At the outboard end of the typical hub assembly, the nearby flange and the brake disk which is attached to it rotate and serve to fling contaminants away from outboard end of the bearing. This supplemental protection does not exist at the inboard end. With four wheel drive vehicles the CV joints provide a measure of protection for the inboard ends of the bearings at the steering knuckles, in that they provide surfaces which function as slingers. But this does not hold true for the inboard ends of the bearings in the steering knuckles of two wheel drive vehicles.